RAD 06 – VHF Direction Finder (VDF)

 

Q1. If, when you are requesting a QDM from an airfield, you are offered a QGH, it means?

The VDF unit is prepared to give you assistance during an approach to the airfield, based on VDF bearings

Q2. %* Given: Compass heading 270, Deviation 2W, Variation 30E, Relative bearing of VDF station from the aircraft 316. What is the QDR?

44

Q3. What may cause a decrease in VDF accuracy?

Site and propagation errors

Q4. #An aircraft wishing to use the VDF service must?

Transmit a signal for a long enough period for the bearing to be established

Q5. * * Which of the following is an advantage of Ground/DF (VDF) let-down?

It only requires a VHF radio to be fitted to the aircraft

Q6. In VDF service the report “QDR 235, Class C” means?

The magnetic bearing from the station to the aircraft is 235+/-10 degrees

Q7. If a ground D/F controller passes a bearing thus: “your true bearing is 256 degrees, class Alpha.” This means..

QTE accurate to +/- 2 degrees

Q8. What is the purpose of a ground direction finder?

To aid pilot navigation

Q9. The range at which you can obtain a VDF bearing can be influenced by?

Aircraft height

Q10. ## What is the minimum level that an aircraft, at a range of 113 NM, must fly in order to contact the tower on R/T for VDF bearing from an airport sited 169 FT above MSL?

FL60

Q11. The pilot of an aeroplane requesting a VDF bearing should?

Avoid banking when transmitting

Q12. *When the pilot is conducting a QDM/QGH procedure, he will require?

An operator on the ground for both QDM (VDF) and QGH procedure in case of VDF, we don’t have any needle/ indicator fitted in the aircraft, so we always require ATC support on RADIO for HOMING.

Q13. # Which of the following statements regarding VHF Direction Finding (VDF) is most accurate?

It uses line of sight propagation

Q14. An aircraft is “tracking away” from a radio beacon whilst maintaining a relative bearing of 180 If the magnetic heading decreases the aircraft is experiencing?

Right drift heading decreases so track is on the right of HDG – drift is right. also you must know for drift assessment – aircraft turns towards the wind.

Q15. **When conducting a QGH approach responsibility for interpreting the procedure rests with…and on a QDM approach, responsibility rests with………?

The controller, the pilot

Q16. One of the uses of the VDF is providing aircraft with?

Homing

Q17. **Understanding required*** In this case, you intercept a QDM that has a right crosswind component. Can you tell if your intercept heading is larger or smaller than it would be without wind influence?

Greater WIND is coming from right to adjust it aircraft correct Hdg to right for wind assessment- hdg increases.

Q18. What airborne equipment, if any, is required to be fitted in order that a VDF let-down may be flown?

VHF radio

Q19. The minimum airborne equipment required for the operation of a VHF Direction Finder is a?

VHF Transmitter-receiver operating in the 118 MHz to 136 MHz range

Q20. ** VDF measures the bearing of the aircraft with?

Reference to the true and magnetic north at the station all the calculation is being done at station.

Q21. What is the effect of multipath signals (coming from the same aircraft) at the Ground VHF Direction Finder Station?

They may result in bearing errors

Q22. Range of VDF depends on? 1. Line of sight formula 2. Power of transmitter 3. Intervening high ground

1, 2 and 3

Q23. *reference to ground DF, the controller can refuse to give a bearing if?

Conditions are poor and bearings do not fall the station’s classifications limits

Q24. *An aircraft is “homing” to a radio beacon whilst maintaining a relative bearing of zero. If the magnetic heading decreases, the aircraft is experiencing?

Right drift

Q25. A radio beacon has an operational range of 10 nm. By what factor should the transmitter power be increased in order to achieve an operational range of 20 nm?

Four

Q26. For ATC to provide a pilot with the aircraft’s location without radar, does it need to have at least?

Two VDFs at different locations, able to take bearings simultaneously on the transmitted frequency

Q27. A VDF may be used?

To provide the ATC controller with bearings of aircraft in the absence of radar

Q28. #Ground direction-finding at aerodromes utilizes which frequencies?

VHF at civil aerodromes, UHF at military aerodromes

Q29. ## If VDF is not affected by the other error which is not listed in this question:——-? The maximum theoretical range at which an aircraft at FL80 can obtain bearings from a ground VDF facility sited 325 FT above MSL is:

134 NM

Q30. Range of VDF depends on? 1. Loudness of the voices of the pilots and the operator when transmitting 2. Power of airborne and ground transmitters 3. Power of pilot voice when transmitting 4. Aircraft altitude and ground transmitter elevation

2 and 4

Q31. #The VDF homer service provides..

Bearings, which will normally be within +/-5 degrees accuracy to a 20 nm range

Q32. # By selecting one VHF frequency, in the range 108 to 112 Mhz, on the Nav receiver?

Rho-theta information from a terminal VOR/DME can be obtained

Q33. Abnormal long ranges may be experienced on VDF channels, caused by?

Super refraction of the signals in the atmosphere ref; Ch 2-super refraction and sub refraction

Q34. A ground direction finding (VDF) may be used to fix the position of an aircraft in which one of the following circumstances?

When using the emergency VHF frequency 121.5 MHz

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